s150 thermostat location

[gokitty199]

hello i believe im having a problem with my thermostat on my s150 and was wondering where it was located so i can replace it. any help would be great

 

[Bobcatdan]

Looking at the engine from the back of the machine, it'd on the right side top of the engine where the upper radiator hose connects. Two bolts remove the thermostat housing. Is it overheating or not warming up? Not saying they can't go bad, but rarely do.

 

[gokitty199]

Looking at the engine from the back of the machine, it'd on the right side top of the engine where the upper radiator hose connects. Two bolts remove the thermostat housing. Is it overheating or not warming up? Not saying they can't go bad, but rarely do.

pretty much i let it warm up at idle as usual for five minutes or so then i drive a few hundred yards to where im moving dirt before i crank the throttle up, it runs normal and cool for about 3-5 minutes and i can put it under heavy load with no issues, then shortly after that the needle on the machine's temp gauge will start going into the yellow and then into the red fairly quickly. it will only rise up to the high temps when its under load, when i empty the bucket and just drive around you can watch the needle fall back down into the green where it used to be when i was running it and its nice and cool. I used it 2 days before for a few hours and it was running just fine as well. the belt that drives the water pump is still tight, hydraulic fluid is full but is dirty(getting filters to change the fluid soon), as well as when it does get hot into the red and i shut the bobcat off i dont hear any coolant boiling or anything and the machine runs as normal. one thing i did notice is that when the temperature gauge has the needle in red that its overheating, if i shut the bobcat off but leave the key on to watch the gauge, the needle does not go back down as if its cooling off it just stays right where it is for a few minutes, but once i start the machine it will go back into the green very quickly.

 

[bruceq]

pretty much i let it warm up at idle as usual for five minutes or so then i drive a few hundred yards to where im moving dirt before i crank the throttle up, it runs normal and cool for about 3-5 minutes and i can put it under heavy load with no issues, then shortly after that the needle on the machine's temp gauge will start going into the yellow and then into the red fairly quickly. it will only rise up to the high temps when its under load, when i empty the bucket and just drive around you can watch the needle fall back down into the green where it used to be when i was running it and its nice and cool. I used it 2 days before for a few hours and it was running just fine as well. the belt that drives the water pump is still tight, hydraulic fluid is full but is dirty(getting filters to change the fluid soon), as well as when it does get hot into the red and i shut the bobcat off i dont hear any coolant boiling or anything and the machine runs as normal. one thing i did notice is that when the temperature gauge has the needle in red that its overheating, if i shut the bobcat off but leave the key on to watch the gauge, the needle does not go back down as if its cooling off it just stays right where it is for a few minutes, but once i start the machine it will go back into the green very quickly.

Some first thoughts: is the system actually overheating or is there a gauge/sender issue. Cooling system can be checked with an infrared thermometer at the sender location. Is the fan moving a sufficient amount of air across the radiator. air in the cooling system... was the coolant low recently? Open the cooling system bleeder and check for trapped air in the system. stuck thermostat... it can be removed and tested in a pot of hot water to ensure it's opening. Or simply check to ensure the upper radiator hose is hot when the engine reaches operating temperature as coolant should be flowing in an open loop at that point. bad radiator cap... if the cooling system is unable to maintain pressure due to a faulty cap it will lose it efficiency and cause overheating. If you have access to a pressure system tester you can check the cap to ensure it holds to the rated psi. Worn water pump... are the water pump shaft bearings worn and getting sloppy. Is the water pump no longer moving a sufficient amount of coolant since it only overheats under load and cools down quickly after the load is reduced. Is the water pump impeller worn to the point of causing cavitation.

 

[walio123]

Some first thoughts: is the system actually overheating or is there a gauge/sender issue. Cooling system can be checked with an infrared thermometer at the sender location. Is the fan moving a sufficient amount of air across the radiator. air in the cooling system... was the coolant low recently? Open the cooling system bleeder and check for trapped air in the system. stuck thermostat... it can be removed and tested in a pot of hot water to ensure it's opening. Or simply check to ensure the upper radiator hose is hot when the engine reaches operating temperature as coolant should be flowing in an open loop at that point. bad radiator cap... if the cooling system is unable to maintain pressure due to a faulty cap it will lose it efficiency and cause overheating. If you have access to a pressure system tester you can check the cap to ensure it holds to the rated psi. Worn water pump... are the water pump shaft bearings worn and getting sloppy. Is the water pump no longer moving a sufficient amount of coolant since it only overheats under load and cools down quickly after the load is reduced. Is the water pump impeller worn to the point of causing cavitation.

In this case I suspect hydraulic cooling fan or what it commands . By increasing the temperature it should increases the speed. You should be able to hear that it rotates faster.

 

[gokitty199]

Some first thoughts: is the system actually overheating or is there a gauge/sender issue. Cooling system can be checked with an infrared thermometer at the sender location. Is the fan moving a sufficient amount of air across the radiator. air in the cooling system... was the coolant low recently? Open the cooling system bleeder and check for trapped air in the system. stuck thermostat... it can be removed and tested in a pot of hot water to ensure it's opening. Or simply check to ensure the upper radiator hose is hot when the engine reaches operating temperature as coolant should be flowing in an open loop at that point. bad radiator cap... if the cooling system is unable to maintain pressure due to a faulty cap it will lose it efficiency and cause overheating. If you have access to a pressure system tester you can check the cap to ensure it holds to the rated psi. Worn water pump... are the water pump shaft bearings worn and getting sloppy. Is the water pump no longer moving a sufficient amount of coolant since it only overheats under load and cools down quickly after the load is reduced. Is the water pump impeller worn to the point of causing cavitation.

we have a infrared thermometer so i will try that but where should i check the temperature? im pulling the thermostat off in a few minutes to test it as well as replacing the rad cap if i have one laying around. i have no idea about the water pump/impeller.

 

[walio123]

we have a infrared thermometer so i will try that but where should i check the temperature? im pulling the thermostat off in a few minutes to test it as well as replacing the rad cap if i have one laying around. i have no idea about the water pump/impeller.

Is hour meter show you some service codes ?

 

[gokitty199]

Is hour meter show you some service codes ?

no it has not

 

[Bobcatdan]

no it has not

Start the thing up and stand beside it right behind the cab. That's where the cooling fan is. Is there a rush off air coming out? Look up in there, is the fan spinning? Sounds like the fan is not running, they will heat up that fast as there is no air going across the radiator. If your decal has two organe bars under the S150, its a G series, they have a belt driven fan, the tensionor probably is shot and threw the belt. If the decal has a soild bar with Bobcat spelled out, its a K series, those have a hydraulic fan. We'll dig into the hydraulic fan if you have one. Otherwise lift up your hydraulic cooler and check for a crap covered radiator.

 

[gokitty199]

Start the thing up and stand beside it right behind the cab. That's where the cooling fan is. Is there a rush off air coming out? Look up in there, is the fan spinning? Sounds like the fan is not running, they will heat up that fast as there is no air going across the radiator. If your decal has two organe bars under the S150, its a G series, they have a belt driven fan, the tensionor probably is shot and threw the belt. If the decal has a soild bar with Bobcat spelled out, its a K series, those have a hydraulic fan. We'll dig into the hydraulic fan if you have one. Otherwise lift up your hydraulic cooler and check for a crap covered radiator.

thank you everyone, it ended up being the alternator belt, when i went out in daylight i saw that it was ripped and just barely hanging on. replaced that and ran it hard and the machine is running cooler than it ever has been.